The present invention refers to soundproofing panels having a high acoustic efficiency to be used in the automotive sector and to their manufacturing procedure.
A wide variety of materials are used to form sound absorbing/insulating structures for use in automobiles. The following patent documents illustrate some of these materials.
U.K. Published Patent Application 2,056,360A to Teroson, GmbH describes a sound insulating/absorbing part having a foam layer formed by placing a plastic material into a mould cavity into localized areas of which have been inserted sheet blanks. The sheets blanks may be formed by a plastic containing a high charge of heavy inorganic fillers, mixtures of polyolefins or EPDM polymers. The foam embeds the blanks which define regions having different sound absorbing/insulating properties.
U.S. Pat. Nos. 4,242,395 and 4,335,034 to Zuckerman et al. describe a thermoplastic composition suitable for use as an automobile carpet backing. The composition contains a high filler content, greater than 60% by weight, 5-25% by weight of an ethylene homopolymer or copolymer, 1-10% by weight of a non-vulcanized elastomeric resin and 1-15% by weight of a plasticizer.
U.S. Pat. No. 4,438,228 to Schenck also illustrates a filled thermoplastic composition useful as sound insulation for an automobile carpet. The compositions are obtained by blending about 5-55% by weight of ethylene .alpha.-olefin copolymer, the .alpha.-olefin containing from 4 to 10 carbon atoms; about 2-12% by weight of plasticizer selected from the group consisting of processing oils, epoxidized oils, polyethers, polyesters and polyether esters; about 40-90% by weight of filler; and optionally elastomeric polymers.
U.K. Published Patent Application 2,072,578A to Toa Nenryo Kogyo KK relates to a carpet having bonded to its rear surface a composition comprising a polyolefin, synthetic rubber, petroleum oil and an organic filler.